|Wildeus, S - VIRGINIA STATE UNIV|
|Collins, J - VIRGINIA STATE UNIV|
Submitted to: Small Ruminant Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 29, 2005
Publication Date: February 3, 2007
Citation: Wildeus, S., Turner, K.E., Collins, J.R. 2007. Growth, Intake, Diet Digestibility, and Nitrogen Use in Three Hair Sheep Breeds Fed Alfalfa Hay. Small Ruminant Research. 69:221-227. Interpretive Summary: Interest in hair sheep production in the U.S. has been increasing because of a declining return on wool production, demand for smaller carcasses in ethnic markets, and use of more forage-based production/finishing systems. We evaluated forage intake and utilization by three hair sheep breeds (Barbados Blackbelly, Katahdin, and St. Croix) when offered alfalfa hay diets. Growth of hair sheep lambs on alfalfa hay diets without energy supplementation was moderate, and did not allow the Katahdin, an improved hair sheep breed, to express its higher growth potential compared to St. Croix. Katahdin lambs utilized available fiber and nitrogen more efficiently than Barbados Blackbelly and St. Croix hair sheep. Breed of hair sheep becomes an important consideration when developing production systems for optimal performance and economics. The information is useful to scientists developing crossbreed hair sheep for use in pasture-based production systems. It will benefit small farm economies by encouraging the use of hair sheep breeds with improved feed nutrient-use efficiency for maximizing small farm income.
Technical Abstract: Pen feeding and metabolism trials were conducted to determine intake, diet digestibility and nitrogen (N) use in three hair sheep breeds with differing growth potential offered an alfalfa hay diet. For pen feeding, 24 6-mo-old wether lambs, equally representing the Barbados Blackbelly, Katahdin, and St. Croix breeds, were paired by breed, placed in 12 enclosed cement-floor pens (2.5 m × 3.5 m), and offered chopped alfalfa (Medicago sativa L.; 17.6% CP, 50.4% NDF, and 36.4% ADF) ad libitum. Lambs were allowed a 14-d adaptation period to pens and diets, and remained on trial for 56 d. Starting body weight (BW) was different (P < 0.05) among breeds (Barbados Blackbelly: 23.8 kg; Katahdin: 36.5 kg; St. Croix: 29.1 kg). Daily gain was not different (P < 0.10) between Katahdin (131 g/d) and St. Croix (117 g/d), but both were higher (P < 0.05) than Barbados Blackbelly (87 g/d). Daily dry matter hay intake was similar among breeds (107–109 g/kg BW0.75), and feed to gain ratio ranged from 8.7 in St. Croix and 9.1 in Katahdin to 10.5 in Barbados Blackbelly, but was not different (P > 0.10) among breeds. Six lambs per breed were used in the metabolism trial. Total DMI was greater (P < 0.01) for Katahdin (1196 g/d) than St. Croix (907 g/d) and Barbados Blackbelly (858 g/d), but was not different (P > 0.10) adjusted for body weight (mean: 71 g/kg BW0.75). Coefficients of apparent digestibility for DM (P < 0.06), OM (P < 0.06), N (P < 0.05), NDF (P < 0.08), and ADF (P < 0.08) were higher for Katahdin compared to Barbados Blackbelly with St. Croix intermediate. Intake of N (P < 0.01), feces N (P < 0.08), urine N (P < 0.01), absorbed N (P < 0.01), and retained N (P < 0.05) also were greater for Katahdin compared to St. Croix and Barbados Blackbelly. Blood glucose, urea-N, and creatinine were not different (P > 0.10) among breeds. Breeds differed in their growth performance in line with breed mature size, and differences were observed in N digestibility and absorption.